Engine cooling fan only works when ac or defrost is on

Take it to a qualified repair shop that has diagnostic information (shop manual ) An has a professional scan tool . Changed what sensor ? Coolant temp ? You don't guess an just replace parts . Doing a full vehicle scan ,checking for DTC'S in all the modules on the vehicle.

ENGINE HOT A/C OFF
Refer to Cooling System Description and Operation
Do the radiator cooling fans work ?
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a Series/Parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block.
During low speed operation, the ECM supplies the ground path for the low speed fan relay, which is Fan 1 Relay, through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the Fan 1 Fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the Series/Parallel relay, which is Fan 2 Relay, and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. The ECM grounds the high speed fan relay, which is Fan 3 Relay and the Series/Parallel relay through the high speed cooling fan relay control circuit. This energizes the Series/Parallel relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized, the relay contacts close to provide battery positive voltage from the Fan 2 Fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
When the requests for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle

DTC P1258: Engine Coolant Overtemperature - Protection Mode Active

Possible bad fuse, relay or switch.

A/C Off For Engine Protection
Refer to Cooling System Description and Operation

DTC P1258: Engine Coolant Overtemperature - Protection Mode Active.
This is something you need to take to a qualified repair shop .
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) or engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood junction block. The ground path is provided at G100.
During low speed operation, the PCM/ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 maxifuse® through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation, the PCM/ECM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM/ECM supplies a ground path for the cooling fan 2 relay and the cooling fan relay through the high speed cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 maxifuse® on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

Most fan and Ac relays are located in the under hood fuse and relay box. Adequately marked in owners manual or on plastic cover

Hi Maria , The A/C system wouldn't keep the fans from running but none working cooling fans will keep the A/C from working ! This is a fairly complex system if your not familiar with this sort of thing ! I will add the description from the factory service manual.
Cooling Fan Control - Two Fan System
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Do you have a check engine light lit ? The thing to do would have it check at the dealer or a ASE certified repair facility ! They could hook up a advanced scan tool an diagnose fairly quick ! Or you could find a wiring diagram an try testing with a volt meter yourself ! But watch yourself so you don't short out the PCM - engine computer !

FAN NOT WORKING

It can be issue with faulty motor or its faulty fan control relay.

Bother are to be inspected.

Test volt at fan relay and fan motor.

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For more help, I suggest you to go through the troubleshooting links mentioned below:-----

Click the link below: ------

How to replace Cooling Fan on Acura Car models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-cooling-fan-on-acura-car.html

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OBD Code P1490 low speed fan relay ckt open-short

http://schematicsdiagram.blogspot.com/2012/11/obd-code-p1490-low-speed-fan-relay-ckt.html

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Engine cooling components working?

http://repairhelpcenter.blogspot.com/2011/11/engine-cooling-components-working.html

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How does Vehicles Engine cooling system works?

http://repairhelpcenter.blogspot.com/2011/11/how-does-vehicles-engine-cooling-system.html

---------------

Hyundai Sonata cooling fan not working

http://schematicsdiagram.blogspot.in/2012/02/hyundai-sonata-cooling-fan-not-working.html

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Fuel pump relay and cooling fan relay troubleshooting on 1997 ford thunderbird?

http://repairhelpcenter.blogspot.com/2011/10/fuel-pump-relay-and-cooling-fan-relay.html

--------------

Fan belt routing diagram for 2004 Volkswagen Jetta?

http://carbeltrouting.blogspot.com/2011/12/fan-belt-routing-diagram-for-2004.html

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Timing belt, drive belt, serpentine belt, accessory belt, fan belt, engine belt routing diagrams for all types of car models?

http://carbeltrouting.blogspot.in/2012/02/timing-beltdrive-beltserpentine.html

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A/C, heater, defroster fan, not working?

http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html

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Blower fan not running on Isuzu trooper?

http://technoanswers.blogspot.in/2012/02/blower-fan-not-running-on-isuzu-trooper.html

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How to replace blower motor fan assembly on 2000 GMC Yukon?

http://repairhelpcenter.blogspot.com/2012/01/how-to-replace-blower-motor-fan.html

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Heater AC or defroster fan not working on KIA?

http://technoanswers.blogspot.in/2012/02/heater-ac-or-defroster-fan-not-working.html

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These will help.

Thanks.

It can be issue with faulty motor or its faulty fan control relay.
Bother are to be inspected.Test volt at fan relay and fan motor.-------------
For more help,i suggest you to go through the troubleshooting links mentioned below:-----Click the link below:------

How to replace Cooling Fan on Acura Car models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-cooling-fan-on-acura-car.html
--------------

OBD Code P1490 low speed fan relay ckt open-short
http://schematicsdiagram.blogspot.com/2012/11/obd-code-p1490-low-speed-fan-relay-ckt.html
---------------

Engine cooling components working?

http://repairhelpcenter.blogspot.com/2011/11/engine-cooling-components-working.html

----------

How does Vehicles Engine cooling system works?

http://repairhelpcenter.blogspot.com/2011/11/how-does-vehicles-engine-cooling-system.html

---------------

Hyundai Sonata cooling fan not working

http://schematicsdiagram.blogspot.in/2012/02/hyundai-sonata-cooling-fan-not-working.html

-------------

Fuel pump relay and cooling fan relay troubleshooting on 1997 ford thunderbird?

http://repairhelpcenter.blogspot.com/2011/10/fuel-pump-relay-and-cooling-fan-relay.html
--------------

Fan belt routing diagram for 2004 Volkswagen Jetta?

http://carbeltrouting.blogspot.com/2011/12/fan-belt-routing-diagram-for-2004.html
---------

Timing belt, drive belt, serpentine belt, accessory belt, fan belt, engine belt routing diagrams for all types of car models?

http://carbeltrouting.blogspot.in/2012/02/timing-beltdrive-beltserpentine.html
-------------

A/C, heater, defroster fan, not working?

http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html
---------

Blower fan not running on Isuzu trooper?

http://technoanswers.blogspot.in/2012/02/blower-fan-not-running-on-isuzu-trooper.html
---------

How to replace blower motor fan assembly on 2000 GMC Yukon?

http://repairhelpcenter.blogspot.com/2012/01/how-to-replace-blower-motor-fan.html
----------

Heater AC or defroster fan not working on KIA?

http://technoanswers.blogspot.in/2012/02/heater-ac-or-defroster-fan-not-working.html
------------These will help.Thanks.

I would suspect a stuck cooling fan relay. Your going to have to locate the malfunction to get the operation that you seek. Reference owners manual for lcoation of the cooling fan relay and try switching it out.

low engine coolant ,coolant temp. switch for the fans,fan relay shorted closed.and possibly a computer.check for codes,coolant level in radiator when cold,remove relay for fan and see if the fan stops. check to see if the ac is on or if the heater ac switch is in defrost position. ac will be on and coolant fan is commanded on also.i hope this will help.

Are we talking about the cooling fans for the engine and AC condenser?? Only one cooling fan will cycle on and off during normal operation. The main cooling fan will cycle on and off as needed for cooling the engine. If you turn on the AC or select a defrost mode on your climate control then the 2nd additional fan will run usually continuously in order to condense the freon in your AC system for cooling the interior of your car and in defrost mode it helps to reduce interior moisture on the glass (defog/ defrost). If no fan comes on at any time whether the engine is hot or cold or whether you turn on the AC or not and you have already replaced a cooling fan relay and checked related fuses then either the fan /s are bad or you dont have power in or out of the fan circuit which consists of several components that would need to be checked. Let us know if you find anything else or have additional questions.